While sausagemeat is, in principal, a mixture of 2 kinds of meat, one fatty and one lean, this is only the basic idea. In France, every good "charcutier" (pork butcher) prepares his own, to a special recipe with his own meats and seasonings.
[Translator's note: French belly bacon ("lard" or "poitrine") is often sold unsliced as a large joint or diced. This is the equivalent of British "streaky" bacon, normally sold ready sliced. Back bacon - such a feature of the great British cooked breakfast - is just not a French thing. Cuts of meat, especially pork, are not always equivalent between the two cultures. I try to translate these on a case-by-case basis that doesn't always suit the website's (very clever) database, so please forgive any ambiguities and inconsistencies that might creep in as a result.].